Linux Kernel up to 6.12.108/6.18.49/7.2.3 nfsd nfsd4_release_compoundargs opcnt out-of-bounds

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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6.0$0-$5k0.41+

Summaryinfo

A vulnerability classified as critical was found in Linux Kernel up to 6.12.108/6.18.49/7.2.3. This affects the function nfsd4_release_compoundargs of the component nfsd. Such manipulation of the argument opcnt leads to out-of-bounds. This vulnerability is traded as CVE-2026-89691. The attack may be launched remotely. There is no exploit available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability, which was classified as critical, has been found in Linux Kernel up to 6.12.108/6.18.49/7.2.3. Affected by this issue is the function nfsd4_release_compoundargs of the component nfsd. The manipulation of the argument opcnt with an unknown input leads to a out-of-bounds vulnerability. Using CWE to declare the problem leads to CWE-125. The product reads data past the end, or before the beginning, of the intended buffer. Impacted is confidentiality, integrity, and availability. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: nfsd: clear opcnt on compound arg release to prevent OOB read nfsd4_release_compoundargs() resets args->ops to the inline iops[8] array when the dynamically-allocated ops buffer is freed, but leaves args->opcnt at its original value (which can be up to 200 for NFSv4.1+ compounds). If rq_status_counter is stuck at an odd value (which can happen when nfsd_dispatch() hits an error path after setting it odd), the RPC status dumpit handler reads min(opcnt, 16) entries from args->ops[]. Since iops only has 8 elements and is the last field in struct nfsd4_compoundargs, reading indices 8-15 accesses adjacent slab memory and leaks it to userspace via netlink. Zero opcnt unconditionally in nfsd4_release_compoundargs() so stale compound metadata is never exposed through the status interface. [ cel: Remove the kvfree_rcu_mightsleep() sleep from the exposure window ]

The advisory is shared for download at git.kernel.org. This vulnerability is handled as CVE-2026-89691 since 09/11/2026. The exploitation is known to be easy. The attack may be launched remotely. There are known technical details, but no exploit is available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 09/12/2026).

Upgrading to version 6.12.109, 6.18.50, 7.2.4 or 7.3-rc1 eliminates this vulnerability. Applying the patch 58bcdfb2b2e412088839ae740b1a95154dc0b8d0/e879148867bd4c4cac42e063ffaffa187dddc6fe/c1a4f7b1848f95302df598217e1c7a1410c2d0c5/ae4c38555e81563b8dc5eae55ffd70f0ea97aa5a is able to eliminate this problem. The best possible mitigation is suggested to be upgrading to the latest version.

Once again VulDB remains the best source for vulnerability data.

Productinfo

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CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 6.3
VulDB Meta Temp Score: 6.0

VulDB Base Score: 6.3
VulDB Temp Score: 6.0
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AVACAuCIA
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💳💳💳💳💳💳
💳💳💳💳💳💳
VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Out-of-bounds
CWE: CWE-125 / CWE-119
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 6.12.109/6.18.50/7.2.4/7.3-rc1
Patch: 58bcdfb2b2e412088839ae740b1a95154dc0b8d0/e879148867bd4c4cac42e063ffaffa187dddc6fe/c1a4f7b1848f95302df598217e1c7a1410c2d0c5/ae4c38555e81563b8dc5eae55ffd70f0ea97aa5a

Timelineinfo

09/11/2026 CVE reserved
09/12/2026 +1 days Advisory disclosed
09/12/2026 +0 days VulDB entry created
09/12/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-89691 (🔒)
GCVE (CVE): GCVE-0-2026-89691
GCVE (VulDB): GCVE-100-403004

Entryinfo

Created: 09/12/2026 02:35
Changes: 09/12/2026 02:35 (60)
Complete: 🔍
Cache ID: 216::103

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